Posted by mike g on August 13, 2002 at 01:49:32:
In Reply to: boxwood shrubs posted by Barry Wiggin on August 08, 2002 at 18:29:09:
It is good to prune your boxwood plants for the first few years to encourage new growth. The time to prune should be as soon as possible; if boxwoods are pruned too late in summer, the new growth might not have time to "mature" before frost hits, and potentially damages, the plants. (depending on your zone).
One way to renew a large, overgrown lilac is to cut the entire plant back to within 6 to 8 inches of the ground in late winter (March or early April). This severe pruning will induce a large number of shoots to develop during the growing season. In late winter of the following year, select and retain several strong, healthy shoots to form the shrub framework and remove all the others at ground level. Head (cut) back the retained shoots to just above a bud to encourage branching.
A second way to prune old lilacs is to cut back the overgrown shrubs over a three-year period. Begin the procedure by removing one-third of the large, old stems at ground level in late winter. The following year (again in late winter), prune out one-half of the remaining old stems. Also, thin out some of the new growth. Retain several well-spaced, vigorous stems and remove all the others. Finally, remove all of the remaining old wood in late winter of the third year. Additional thinning of the new shoots should also be done. Since lilac wood needs to be 3 or more years of age before it blooms, this pruning method should allow you to enjoy flowers every spring.